Metal oxide films, such as indium oxide and indium-tin oxide, are known to be optically transparent and electrically conductive. Transparent and electrically conductive films are used, for example, in solar thermal energy conversion, solar photovoltaic conversion, solar heating, static control films, laser resistant coatings in high power laser technology, as the photocathode in photoelectrochemical cells, and as surface layers in electroluminescent applications. See, A. L. Dawer, S. G. Joshi, Review of semiconducting transparent thin films; their properties and applications, Journal of Materials Science, 19 (1984) pp. -23.
While the utility of metal oxide films has been well known, processes for manufacturing metaloxide films have been slow and expensive. Indium oxide and indium-tin oxide are two well-known metal oxides which can be formed into thin layers having low electrical resistance and high optical transparency. Indium oxide and indium-tin oxide films can be made by, for example, magnetron sputtering or by evaporating indium or indium tin oxide onto a substrate in an atmosphere containing carefully controlled amounts of oxygen and argon. However, these processes are very slow and difficult to control and, therefore, are quite expensive.
Therefore, there is a need for a process by which coatings of metal oxides, such as indium oxide or indium tin oxide, can be produced quickly and economically. Further, there is a need for producing metal oxide coatings which are electrically conductive and allow sufficient amounts of visible light to pass through the coating. The present invention provides a fast and economical process for forming a metal oxide film which is supported between a substrate and a protective polymeric coating.